Automobiles and similar vehicles are often the most expensive personal property a person owns. For this reason pride is usually taken in their cleanliness. Many people, however, do not have the time and/or place to wash a car, and the great increase in labor cost over recent years has made it prohibitively expensive to hire someone to wash a vehicle.
In repsonse to these problems, various types of automatic and semiautomatic vehicle washing systems have been developed to facilitate fast and inexpensive car washing. One type of system uses high pressure water jets deployed around a washing bay to alternately spray the vehicle with soapy water and rinse water. This system may be adequate for a vehicle with loose dirt, but heavy road grime is not, however, adequately cleaned. The results of this sytem therefore leave much to be desired, particularly in areas shielded from direct water jet action.
A second primary method utilizes a plurality of long bristle brushes to scrub away dirt, highway grime, and other hard to loosen materials. These brushes are disposed in various positions around a vehicle. Historically, side or vertically disposed brushes have been either single or double brushes located on each side of the vehicle wash bay. Single side brushes are usually mounted on a vertical shaft and have bristles extending from a point near the ground to the highest point of any vehicle that the machine is adapted to clean. This arrangement is often further modified by the use of multiple side brushes. The use of two vertical brushes on each side allows the upper brush to be cut off when washing the front and rear portions of the vehicle. To accomplish this purpose the tandem side brushes have invariably been driven by one or more motors mounted above the side brushes. Usually, the bottom brush is driven by a shaft of other means passing through a hollow upper brush assembly. This provides an indirect drive system which is cumbersome, difficult to repair, subject to frequent breakdowns, and more costly to construct and operate than a direct drive system.
Horizontally disposed, overhead pivoting brushes for washing the front, rear, and top of the vehicle have long been used in conjunction with side brushes. These pivoting horizontal brushes may be hydraulically or pneumatically positioned. Alternatively, they are in some systems counterbalanced by weights suspended from the brush arm and allowed to pivot freely during the wash sequence. The brushes thus move as they encounter the vehicle surface.
It has been nearly impossible to achieve accurate control of hydraulic or pneumatically operated overhead brushes. This has resulted in vehicle damage or unsatisfactory wash results. Moreover, in the counterbalance system, the amount of pressure required to move the brush when the brush arms hang vertically is much less than the pressure required when the brush arms swing upwardly. Only slight pressure is required to move the horizontal brush when its brush arms are nearly vertical. This characteristic greatly reduces the cleaning ability of such brushes against the front and rear of a vehicle. On the other hand, increased pressure is requird to move the brushes as the support arms pivot upwardly. This causes excessive cleaning pressure which may damage the finish on the vehicle and even cause structural damage.
The problem thus encountered by pivotable brush arms is that the total moment varies greatly as the brush arm pivots from its lowermost position to its uppermost position. Prior art discloses several attempts to normalize the variations in this moment. Some designs use multiple counterweights as shown in U.S. Pat. No. 4,470,167 to Bivens. Other devices, like that shown in U.S. Pat. No. 3,816,869 to Ennis, use a movable counterweight. All of these devices have a drawback, however, in that the heavy weights required create high load on the brush arm and frame.
A further problem found in vehicle washes of all types is the difficulty in properly centering the vehicle within the wash bay before beginning the washing process. One method uses guide rails to lead the vehicle into the wash bay. These guide rails must be spaced widely enough to accept various tire widths and therefore allow several inches latitude to vehicles with narrower tires. Since vehicle width also varies drastically, these rails, which are usually fixed, must be set to accommodate a vehicle of average width. This is at best a compromise and necessarily allows lateral variation in vehicle placement.
Other car wash systems simply require the vehicle drive to center the vehicle in the machine without the aid of any helpful devices. A driver must aim for a small treadle switch on the floor of the wash bay which must be activated to begin the wash sequence. Few drivers, however, are capable of bringing their car to the enter of the wash bay without outside aid. The considerble lateral varation allowed by either of these centering methods can cause problems in the washing process and will produce an uneven wash.